napi-macros

Set of utility macros to make writing N-API modules a little easier.

``
npm install napi-macros
`

Then add the following to your target in your binding.gyp file

`
"include_dirs": [
"],
`

These patterns mostly reflect how I use N-API so far. Feel free
to PR more.

Usage

` c
#include
#include

NAPI_METHOD(times_two) {
NAPI_ARGV(1)
NAPI_ARGV_INT32(number, 0)

number *= 2;

NAPI_RETURN_INT32(number)
}

NAPI_INIT() {
NAPI_EXPORT_FUNCTION(times_two)
}
`

Full working example can be found in the example/ folder.

API

#### NAPI_INIT()

Setup init boilerplate. Pass the function body after.

` c
static char *my_string = "hello";

NAPI_INIT() {
EXPORT_STRING(my_string)
}
`

#### NAPI_METHOD(name)

Setup method boilerplate. Pass the function body after.

` c
NAPI_METHOD(add) {
NAPI_ARGV(2)
NAPI_ARGV_INT32(a, 0)
NAPI_ARGV_INT32(b, 1)

a = a + b

NAPI_RETURN_INT32(a)
}
`

#### NAPI_ARGV(n)

Setup up argv boilerplate. n is how many arguments you are expecting.
Expects the napi_env to be in scope as env and the napi_callback_info to be in scope as info.

#### NAPI_ARGV_BUFFER(name, index)

Get a buffer out of the arguments at the corresponding index.
Sets char *name and size_t name_len with the buffer and buffer length.

#### NAPI_ARGV_BUFFER_CAST(type, name, index)

Get a buffer out and cast the pointer to the specified type.
Note that the type should include the pointer star, i.e.

` c
NAPI_ARGV_BUFFER_CAST(uv_udp_t *, handle, 0)
`

Will cast the 1st argument as uv_udp_t pointer.

#### NAPI_ARGV_UINT32(name, index)

Get an argument as a uint32.
Will throw if argument is not the right type.

#### NAPI_ARGV_INT32(name, index)

Get an argument as an int32.
Will throw if argument is not the right type.

#### NAPI_ARGV_UTF8(name, length, index)

Get an argument as a utf8 string.

name will be a char[length] array.

Will throw if argument is not the right type.

#### NAPI_ARGV_UTF8_MALLOC(name, index)

Get an argument as a utf8 string.

name will be a char*.

Like NAPI_ARGV_UTF8() but allocates name on the heap using malloc(), which should be free()'d after usage.

#### NAPI_BUFFER_CAST(type, name, var)

Same as NAPI_ARGV_BUFFER_CAST but takes a generic napi_value variable instead of an argv index.

#### NAPI_BUFFER(name, var)

Same as NAPI_ARGV_BUFFER but takes a generic napi_value variable instead of an argv index.

#### NAPI_UTF8(name, size, var)

Same as NAPI_ARGV_UTF8 but takes a generic napi_value variable instead of an argv index.

#### NAPI_UTF8_MALLOC(name, var)

Same as NAPI_ARGV_UTF8_MALLOC but takes a generic napi_value variable instead of an argv index.

#### NAPI_UINT32(name, var)

Same as NAPI_ARGV_UINT32 but takes a generic napi_value variable instead of an argv index.

#### NAPI_INT32(name, var)

Same as NAPI_ARGV_INT32 but takes a generic napi_value variable instead of an argv index.

#### NAPI_EXPORT_FUNCTION(fn)

Will export a function in the Init method. Expects the env and exports to be in scope.
The name of the exported function is the same name as the c function.

#### NAPI_EXPORT_SIZEOF(struct)

Export the size of a strict. The exported name is sizeof_{struct-name}.

#### NAPI_EXPORT_UINT32(name)

Export a uint32.
The name of the exported number is the same name as the c variable.

#### NAPI_EXPORT_INT32(name)

Export an int32.
The name of the exported number is the same name as the c variable.

#### NAPI_EXPORT_UTF8(name, len)

Export a utf8 string. len should be the length of the string.
The name of the exported string is the same name as the c variable.

#### NAPI_EXPORT_STRING(name)

Export a null terminated string.
The name of the exported string is the same name as the c variable.

#### NAPI_EXPORT_SIZEOF(type)

Exports sizeof(type).
The name of the exported number is the same name as the c variable.

#### NAPI_EXPORT_SIZEOF_STRUCT(structName)

Exports sizeof(struct structName).
The name of the exported number is the same name as the c variable.

#### NAPI_EXPORT_ALIGNMENTOF(type)

Exports the byte alignment of type.
The name of the exported number is the same name as the c variable.

#### NAPI_EXPORT_ALIGNMENTOF_STRUCT(structName)

Exports the byte alignment of struct structName.
The name of the exported number is the same name as the c variable.

#### NAPI_EXPORT_OFFSETOF(type, name)

Exports the byte offset of name within type.
The name of the exported number is the same name as the c variables.

#### NAPI_EXPORT_OFFSETOF_STRUCT(structName, name)

Exports the byte offset of name within struct structName.
The name of the exported number is the same name as the c variables.

#### NAPI_FOR_EACH(array, element)

Iterate over an array. array should be a napi_value containing a javascript array
and element is the variable name an element will be exposed as. Expects the loop body
to be passed after.

` c
napi_value buffers = argv[0] // first argument is a js array
NAPI_FOR_EACH(buffers, buffer) {
NAPI_BUFFER(cbuf, buffer)
printf("cbuf is now a char * pointer: %s\n", cbuf);
}
`

#### NAPI_RETURN_UINT32(name)

Returns a uint32.

#### NAPI_RETURN_INT32(name)

Returns an int32.

#### NAPI_RETURN_UTF8(name, len)

Return a utf8 string. len should be the length of the string.

#### NAPI_RETURN_STRING(name)

Return a null terminated string.

#### NAPI_STATUS_THROWS(call)

Checks the return status of any napi_* function returning a napi_status type. This simplifies using a napi_status variable and comparing the result with napi_ok. It's used internally but can be used stand alone as well.

`c
NAPI_STATUS_THROWS(
napi_create_threadsafe_function(
NULL,
callback,
0,
async_resource_name,
0,
3,
0,
my_finalize,
NULL,
my_callback,
&threadsafe_function
)
);
`

Above example will fail because the first env parameter is NULL and throw the following error:

`
Error: napi_create_threadsafe_function(NULL, callback, 0, async_resource_name, 0, 3, 0, my_finalize, \
NULL, my_callback, &threadsafe_function) failed!
`

#### NAPI_UV_THROWS(err, fn)

Checks if a libuv call fails and if so, throws an error.

` c
int err;
NAPI_UV_THROWS(err, uv_ip4_addr((char *) &ip, port, &addr))
`

#### NAPI_MAKE_CALLBACK(env, async_ctx, ctx, func, argc, argv, result)

Same as napi_make_callback except it checks if the JS function throw an exception
and triggers a process.on('uncaughtException')` if so.

License

MIT